NCT04339374 · Washington University School of Medicine
Ultrasound and Photoacoustic Imaging for Enhanced Differential Diagnosis of Rectal Cancer
What this study is about
The purpose of this study is to demonstrate the functionality of a novel endorectal photoacoustic ultrasound imaging modality in humans with rectal cancer. The study involves testing a previously developed endorectal device to determine its ability to accurately assess rectal tumor response to preoperative treatment.
View original scientific description
The purpose of this study is to demonstrate the functionality of a novel endorectal photoacoustic ultrasound imaging modality in humans with rectal cancer. The study involves testing a previously developed endorectal device to determine its ability to accurately assess rectal tumor response to preoperative treatment. Investigators hypothesize that a co-registered photoacoustic ultrasound endorectal device can significantly reduce unnecessary surgeries in rectal cancer patients with complete clinical response while maintaining high sensitivity in identifying those with residual cancer.
Interventions
DEVICE
Photoacoustic imaging, photoacoustic microscopy
-Emerging technique in which a short-pulsed laser beam penetrates diffusely into a tissue sample, causing the release of acoustic waves due to a transient temperature rise -The transient acoustic waves, or photoacoustic waves, are then measured around the sample by US transducers -The resolution of the devices can be altered by changing the wavelengths of laser light and spectrum analysis of the receiver. In this manner, human colorectal pathology will be examined under multiple types of photoacoustic ranges (broadly termed photoacoustic microscopy and photoacoustic imaging). The study has two phases. In the second phase, the investigators will provide assessments of treated rectum based on clinical information and photoacoustic information after initial training.
DEVICE
Endorectal photoacoustic imaging probe
-An endorectal imaging device using coregistered photoacoustic and ultrasound imaging has been constructed. This probe is used to perform in vivo imaging among patients with rectal pathology intraoperatively.
OTHER
Reader Performance
After initial training using Group 1 data, readers will classify lesions as non-clinical complete responders (non-cCR) or clinical complete responders (cCR) based on standard-of-care (SOC) information. Following PAM/US imaging, readers will reassess lesion status using PAM/US data. PAM/US model outputs will be generated for each patient and compared with reader assessments. For patients undergoing surgery, tumor regression scores from surgical specimens will be compared with reader assessments and model outputs. For patients under nonoperative surveillance, clinical response at 2-year follow-up will be compared with model outputs. The study will evaluate whether PAM/US assistance improves residual tumor detection in Group 2 patients. As the model is under development, it will be iteratively retrained and tested as new data become available.
Primary outcome measures
Number of patients that readers are able to diagnose with rectal cancer
Time frame: Approximately 15 minutes
The primary endpoint is to see if the readers trained to use the co-registered PAM/US data are able to diagnose rectal cancers with better sensitivity \& specificity using surgery pathology results as the ground truth. SOC sensitivity and specificity will be computed based on readers' cCR vs. non-cCR. The sensitivity and specificity with additional PAM/US data will be computed based on readers' revised cCR vs. non-cCR. PAM/US model sensitivity and specificity will also be computed using surgery pathology results.
Number of patients without surgery who cleared as cCR after 2-years of follow-up
Time frame: 2-years of follow-up
The secondary primary endpoint is the sensitivity and specificity of readers' cCR vs. non-cCR assessments using SOC and sensitivity and specificity of PAM/US models cCR vs. non-cCR reassessments PAM/US data. The "ground truth " of this cohort will be no cancer recurrence based on clinical data.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Patients with any stage of rectal cancer undergoing surgical resection.
- Age \>18 years
- Able to provide informed consent Additional Inclusion Criterion for in vivo imaging (patients):
- Lesion located within 15cm of the anal verge
Exclusion criteria
- Inability to provide consent
- Collection of intraoperative specimen for frozen section analysis will disqualify patients from participation Eligibility Criteria Readers:
- Colorectal surgeons or radiologists who treat or interpret imaging regularly for patients with rectal cancer.
Where
- St Louis, Missouri
Collaborators
National Institute for Biomedical Imaging and Bioengineering (NIBIB)
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Feb 12, 2026 · Source of record for eligibility and locations